In 2023, researchers in a West African nation tried to discover which pizza do lizards prefer and won an Ig Nobel Prize for its discovery

Imagine setting out to study the feeding habits of lizards and ending up discovering that they have a clear preference for one type of pizza over another. It may sound like the plot of a comedy, but it became the basis of a real scientific study, and eventually earned its researchers one of science's most unusual honors, the 2025 Ig Nobel Prize in Nutrition.

The 2023 study, published in the African Journal of Ecology, documented how rainbow lizards (Agama agama) living near a beach resort in Togo repeatedly ignored their usual insect diet in favor of leftover pizza. Even more surprisingly, when given a choice, every observed lizard chose the same variety: four-cheese pizza.

While the finding made headlines for its humor, researchers say it offers genuine insight into how wildlife adapts to human environments and how urbanization is reshaping animal behavior.

The unusual experiment that caught the world's attention

The research, led by Daniele Dendi, Gabriel H. Segniagbeto, Roger Meek and Luca Luiselli, focused on a population of rainbow lizards living around a seaside resort in southern Togo, West Africa.

Rainbow lizards are widespread across sub-Saharan Africa and primarily feed on insects such as ants, termites and beetles. However, because they often live close to human settlements, scientists wanted to investigate whether they had begun exploiting human food in tourist areas.

For the field experiment, the researchers observed nine rainbow lizards (Agama agama) over two days. The group included five adults, three males and two females, and four subadults or juveniles.

To test whether the reptiles showed a food preference, the team simultaneously placed two different types of pizza on the ground, a four-cheese pizza and a four-seasons pizza. The plates were positioned about 10 metres apart and roughly 10 metres from trees where the lizards had previously been spotted. Researchers monitored the animals from a distance of around 15 metres to avoid influencing their behaviour.

Within 15 minutes, the lizards began approaching the food. Some sprinted from as far as 15 metres away, while others jostled and even fought over access to the pizza. The feeding frenzy continued for nearly two hours.

The most striking finding was that all nine monitored lizards, regardless of whether they were adults or juveniles, consistently chose the four-cheese pizza, leaving the four-seasons pizza largely untouched. According to the researchers, such unanimous preference suggests the animals may have been responding to chemical cues, such as smell, or to nutritional characteristics unique to the cheese-rich pizza.

Why would an insect-eating lizard choose cheese pizza?

The researchers did not conclude that rainbow lizards naturally prefer pizza or dairy products. Instead, they proposed several scientific explanations.

One possibility is that the lizards responded to chemical cues, such as the smell of cheese or fats, making the four-cheese pizza more attractive.

Another explanation is nutritional. Cheese-rich food contains high levels of fat and calories compared with insects. The researchers suggested that the four-cheese pizza may have provided nutrients or energy that were easier for the lizards to obtain, although this hypothesis requires further study.

Importantly, the study did not determine whether eating pizza is beneficial or harmful for the reptiles. Instead, the authors suggested future research should examine whether lizards regularly consuming human food differ in body condition or health from nearby populations that continue eating their natural insect diet.

A glimpse into how wildlife adapts to humans

Beyond the amusing headline, the study illustrates a broader ecological phenomenon known as opportunistic foraging. Many wild animals alter their feeding behavior when humans introduce abundant, calorie-rich food into their habitats.

Previous studies have documented seagulls stealing fast food from beachgoers, urban foxes feeding from garbage bins, bears seeking food at campsites, monkeys raiding tourist areas and crows learning to exploit city waste.

Rainbow lizards appear to be another example of a species rapidly adapting to human-altered environmentInterestingly, this is not the first time researchers have reported unusual eating habits in these reptiles. Earlier observations from Gabon and Ghana recorded rainbow lizards consuming bread, suggesting that the species is capable of incorporating processed human food into its diet when opportunities arise.

The study earned an Ig Nobel Prize

The pizza experiment later received an Ig Nobel Prize. Presented every year by the science humor magazine Annals of Improbable Research, the Ig Nobel Prizes honor studies that "first make people laugh, and then make them think." The ceremony is traditionally held at Harvard University, where Nobel laureates often take part in presenting the awards.

Despite its lighthearted reputation, the prize recognizes real, peer-reviewed scientific research. Many winning studies investigate unusual or seemingly trivial questions, but they often uncover meaningful insights into biology, medicine, psychology, engineering or human behavior.